Modular header system

ABSTRACT

The present invention provides a header module adapted for use with a retail store refrigeration system including a plurality of refrigerated merchandisers. The header module includes a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant received from the plurality of refrigerated merchandisers and a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant for discharge to the plurality of refrigerated merchandisers. The first and second conduits are integrally formed.

FIELD OF THE INVENTION

This invention relates generally to a refrigeration system, and more particularly to a refrigeration system comprising one or more refrigerated merchandisers or refrigerated display cases.

BACKGROUND OF THE INVENTION

Retail store refrigeration systems typically comprise a plurality of refrigerated merchandisers to store refrigerated products in a retail area. Each refrigerated merchandiser typically includes one or more evaporators to cool the airflow circulating through the merchandiser. However, the other components of the refrigeration system, such as one or more compressors and condensers, are typically located in an area of the retail store separate from the retail area. To transport compressed liquid refrigerant from the outlet of the condenser to the plurality of merchandisers in the retail area, a complete header system is typically constructed from copper tubing and conventional valves for each merchandiser. Such a complete header system is sufficient to transport refrigerant to and from the evaporator in the merchandiser during both a refrigeration cycle and a defrost cycle.

Each complete header system typically includes a suction header, which allows multiple suction lines from the merchandiser lineups to be distributed to the suction inlet of multiple compressors serving that suction group. A complete header system also typically includes a liquid header, which provides a common compressed liquid refrigerant from the condenser outlet, to be distributed among multiple branch liquid lines serving the merchandiser lineups. A complete header system further includes a gas defrost header which allows superheated refrigerant from the compressor to flow through the merchandiser's evaporators during a defrost cycle. The suction header, liquid header, and the gas defrost header are typically custom-made for each retail store refrigeration system using skilled labor. Sections of copper tubing are brazed together to form the headers, sometimes on-site in the retail store.

SUMMARY OF THE INVENTION

The present invention provides, in one aspect, a header module adapted for use with a retail store refrigeration system including a plurality of refrigerated merchandisers. The header module includes a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant received from the plurality of refrigerated merchandisers and a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant for discharge to the plurality of refrigerated merchandisers. The first and second conduits are integrally formed. In some embodiments, an integrally-formed third conduit defines at least a portion of a common gas defrost header and is adapted to carry superheated, compressed gaseous refrigerant for selective discharge to the plurality of refrigerated merchandisers.

The present invention provides, in another aspect, a modular header system adapted for use with a retail store refrigeration system. The modular header system includes a first header module having a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant and a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant. The first conduit and second conduit of the first header module are integrally formed. The modular header system also includes a second header module having a first conduit defining at least a portion of the common suction header and a second conduit defining at least a portion of the common liquid header. The first conduit and second conduit of the second header module are integrally formed. The second header module is coupled to the first header module to fluidly couple the first conduits of the common suction header and the second conduits of the common liquid header.

The present invention provides, in yet another aspect, a method of assembling a retail store refrigeration system including a plurality of refrigerated merchandisers. The method includes providing first and second header modules, interconnecting the second header module with the first header module, and fluidly coupling the first conduits of the common suction header and the second conduits of the common liquid header.

Other features of the invention will become apparent to those skilled in the art upon review of the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a header module of the present invention.

FIG. 2 is a reverse perspective view of the header module of FIG. 1.

FIG. 3 is a cross-sectional view through section line 3-3 of the header module of FIG. 1.

FIG. 4 is a schematic illustrating the header module of FIG. 1 incorporated into a retail store refrigeration system.

Before any features of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including”, “having”, and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order.

DETAILED DESCRIPTION

FIGS. 1 and 4 illustrate a header module 10 adapted to fluidly connect one or more evaporators 14 in a refrigerated merchandiser 18 with other components in a retail store refrigeration system, such as one or more compressors 22 and condensers 26. In such a retail store refrigeration system, the refrigerated merchandiser 18 is located in a retail area, while the compressors 22 and condensers 26 can be located in an area of the retail store separate from the retail area. For example, the compressors 22 may be located in a machine room separate from the retail area, and the condensers 26 may be positioned on a rooftop of the retail store.

As shown in FIG. 1, the header module 10 includes a pre-assembled unit or body 30, made from plastic, metal, or other material, that incorporates a suction valve system in communication with a suction conduit 38, a liquid delivery valve system in communication with a liquid conduit 46, and a gas defrost valve system in communication with a gas defrost conduit 54. The suction conduit 38, liquid conduit 46, and the gas defrost conduit 54 are integrally formed with the body 30 and each other. A plurality of header modules 10 may be interconnected, such that the plurality of suction conduits 38, liquid conduits 46, and gas defrost conduits 54 form a common suction header 58, a common liquid header 62, and a common gas defrost header 66, respectively, of a desired length (see FIG. 4). In some embodiments, header modules 10 only include two of the three common headers 58, 62, 66. For example, the header modules 10 can include only common suction and liquid headers 58, 62.

With reference to FIG. 1, the plurality of interconnected header modules 10 may provide a separate valve system for each respective refrigerated merchandiser 18 in the retail store. The header modules 10 are interconnected by mating end plates 70 that are fastened together by inter-engaging keys 74 and keyways 78. In the illustrated construction of the header module 10, the keys 74 and keyways 78 are configured in a dove-tail shape. Alternatively, typical fasteners such as bolts or clamps may be used to interconnect the header modules 10. On each header module 10, O-rings 82 may be positioned at one or both ends of the suction conduit 38, liquid conduit 46, and the gas defrost conduit 54 to seal against an adjacent suction conduit 38, liquid conduit 46, and gas defrost conduit 54 of adjacent header modules 10.

With reference to FIGS. 3 and 4, the suction valve system is in fluid communication between the evaporators 14 and the compressor 22. The suction valve system includes a suction coupling 86 positioned within a bore 90 of the body 30, a controllable suction valve 94 positioned within a bore 98 of the body 30, and a suction isolation valve 102 positioned within a bore 106 of the body 30. The bores 90, 98 are in fluid communication with one another via a connecting passage 92, while the bores 98, 106 are in fluid communication with one another via another connecting passage 104. The bore 106 is in fluid communication with the suction conduit 38 via yet another connecting passage 108. As such, a combination of the bores 90, 98, 106 and connecting passages 92, 104, 108 generally define a suction inlet passageway. In operation, when the suction isolation valve 102 is open, the suction valve 94 may be automatically or manually controlled to regulate the amount of low-pressure, gaseous refrigerant that is received from the remote evaporators 14 through the suction coupling 86 and discharged to the suction header 58.

The suction valve 94 may, in one construction of the header module 10, be a suction-stop EPR valve controlled by a solenoid (not shown) to either open the suction-stop EPR valve to regulate the flow across the suction-stop EPR valve or close the suction-stop EPR valve. In addition, the suction valve 94 may be, in another construction of the header module 10, a non-suction stop EPR valve that is either manually opened to regulate the flow across the non-suction stop EPR valve or closed. Alternatively, the suction valve 94 may be replaced by a suction-stop solenoid that may be selectively opened to allow unregulated flow therethrough. The controllable suction valve 94 may be a cartridge-type valve. Such a cartridge-type valve is available from the Parker Hannifin Corporation. Alternatively, the suction valve 94 may be an electronically controlled valve, such as a screw-operated valve actuated by a servo-motor.

The suction isolation valve 102 may be utilized during servicing of the corresponding refrigerated merchandiser 18 to, for example, isolate the refrigerated merchandiser 18 from the rest of the refrigerated merchandisers 18 in the retail store refrigeration system. In other words, when the suction isolation valve 102 is closed, the flow of low-pressure gaseous refrigerant through the suction inlet passageway is blocked. This may be desirable when repairing or replacing the evaporator(s) 14 in the refrigerated merchandiser 18, or when repairing or replacing the controllable suction valve 94. The suction isolation valve 102 may be, for example, a quarter-turn ball valve that may be manually opened and closed. Such a quarter-turn ball valve is also available from the Parker Hannifin Corporation.

With reference to FIGS. 3 and 4, the liquid delivery valve system is in fluid communication between the liquid header 62 and the evaporator(s) 14 in the refrigerated merchandisers 18. The liquid delivery valve system includes a liquid coupling 110 positioned within a bore 114 of the body 30, a controllable liquid valve 118 positioned within a bore 122 of the body 30, and a liquid isolation valve 126 positioned within a bore 130 of the body 30. The bores 114, 122 are in fluid communication with one another via a connecting passage 116, while the bores 122, 130 are in fluid communication with one another via another connecting passage 124. The bore 130 is in fluid communication with the liquid conduit 46 via yet another connecting passage 132. As such, a combination of the bores 114, 122, 130 and connecting passages 116, 124, 132 generally define a liquid outlet passageway. In operation, when the liquid isolation valve 126 is open, the liquid valve 118 may be automatically or manually controlled to regulate the amount of compressed liquid refrigerant that is allowed to flow to the remote evaporators 14 through the liquid coupling 110 from the liquid header 62.

Like the suction valve 94, the liquid valve 118 may be a liquid-stop valve controlled by a solenoid (not shown), a non-liquid stop valve that is manually adjusted, a liquid-stop solenoid, a cartridge-type valve, or an electronically controlled valve, such as a screw-operated valve actuated by a servo-motor.

Like the suction isolation valve 102, the liquid isolation valve 126 may be utilized during servicing of the corresponding refrigerated merchandiser 18. The liquid isolation valve 126 may also be, for example, a quarter-turn ball valve that may be manually opened and closed.

With continued reference to FIGS. 3 and 4, the gas defrost valve system is in fluid communication between the outlet of the compressor 22 and the remote evaporators 14 through the suction coupling 86. In some embodiments, the gas defrost valve system is in fluid communication with the outlet of the compressor 22 while in other embodiments the gas defrost valve system is in fluid communication with a receiver RC downstream of the condensers CN. Also, in other embodiments, the gas within the common gas defrost header 66 can be used as a high pressure source to operate certain pilot valves (such as a high pressure source to modulate the piston of a electronic pressure regulating valve).

The gas defrost valve system includes a controllable gas defrost valve 134 positioned within a bore 138 of the body 30, and a gas defrost isolation valve 142 positioned within a bore 146 of the body 30. The bores 90, 138 are in fluid communication with one another via a connecting passage 140, while the bores 138, 146 are in fluid communication with one another via another connecting passage 148. The bore 146 is in fluid communication with the gas defrost conduit 54 via yet another connecting passage 152. As such, a combination of the bores 90, 138, 146 and connecting passages 140, 148, 152 generally define a gas defrost passageway. In operation, when the gas defrost isolation valve 142 is open, the gas defrost valve 134 may be automatically or manually controlled to regulate the amount of superheated, compressed gaseous refrigerant that is discharged to the remote evaporators 14 through the suction coupling 86 from the outlet of the compressor 22.

Like the suction valve 94 and the liquid valve 118, the gas defrost valve 134 may be a vapor-stop valve controlled by a solenoid (not shown), a non-vapor stop valve that is manually adjusted, a vapor-stop solenoid, a cartridge-type valve, or an electronically controlled valve, such as a screw-operated valve actuated by a servo-motor.

Like the suction isolation valve 102 and the liquid isolation valve 126, the gas defrost isolation valve 142 may be utilized during servicing of the corresponding refrigerated merchandiser 18. The gas defrost isolation valve 142 may also be, for example, a quarter-turn ball valve that may be manually opened and closed.

The valves 94, 102, 118, 126, 134, 142 and the couplings 86, 110 are joined to the body 30 by fastening mating flanges 150 together. Alternatively, other fastening structure may be utilized to secure the valves 94, 118, 134 and the couplings 86, 110 to the body 30, such as threaded fittings and/or quick-release fittings.

With reference to FIG. 4, a schematic illustrating a retail store refrigeration system incorporating the header module 10 of the present invention is shown. For illustrative purposes only, FIG. 4 shows only two header modules 10. However, it should be understood that any number of header modules 10 may be interconnected in the retail store refrigeration system. In addition, a controller (not shown) may be electrically connected to one or more of the header modules 10 to control operation of one or more of the suction valve 94, liquid valve 118, and the gas defrost valve 134.

A first header module H1 is shown in fluid communication with a first refrigerated merchandiser M1. Although not shown in FIG. 4, an adapter plate including a suction header coupling, a liquid header coupling, and a gas defrost header coupling is coupled to the first header module H1. The adapter plate includes keyways configured to receive the dovetail-shaped keys 74 engaged with the first header module H1. The O-rings 82 (see FIG. 1) on the first header module H1 respectively seal the suction header coupling to the suction header 58, the liquid header coupling to the liquid header 62, and the gas defrost header coupling to the gas defrost header 66.

Respective refrigeration lines R1, R2, R3 may be fluidly connected to the couplings to transport refrigerant to the first header module H1 or away from the first header module H1. Such refrigeration lines R1, R2, R3 may be formed from copper tubing that is inserted into the couplings and brazed to the couplings. Alternatively, the couplings may include quick-release structure to fluidly connect with the refrigeration lines R1, R2, R3, or the couplings may include structure requiring hand tools to fluidly connect with the refrigeration lines R1, R2, R3.

With continued reference to FIG. 4, a second header module H2 is shown in fluid communication with a second refrigerated merchandiser M2. The second header module H2 may directly interconnect with the first header module H1 by inter-engaging the keys 74, or, alternatively, additional header modules 10 may be positioned between the first and second header modules H1, H2 to fluidly communicate with additional refrigerated merchandisers 18.

If the second header module H2 is to be the last module 10 in a line or system of interconnected modules 10, an end plate 154 may be utilized to close or cap the ends of the respective headers 58, 62, 66. Although the end plate 154 is shown schematically in FIG. 4, the end plate 154 may include dovetail-shaped keyways to inter-engage the dovetail-shaped keyways 78 of the second header module H2 via keys 74. The end plate 154 may also include O-rings to seal the respective headers 58, 62, 66 to the end plate 154.

Other components in the retail store refrigeration system are also shown in FIG. 4. The suction inlet of a compressor C is fluidly connected to the suction header coupling via the refrigeration line R1. Alternatively, more than one compressor 22 may be utilized in either a parallel or series arrangement. For example, two or three header modules 10 may be utilized for each compressor 22 in the refrigeration system. From the discharge outlet of the compressor C, another refrigeration line R4 fluidly connects the compressor C with the inlet of a condenser CN to discharge compressed gaseous refrigerant to the condenser CN. Alternatively, more than one condenser CN may be utilized in either a parallel or series arrangement. In addition, the refrigeration line R2 is fluidly connected to the outlet of the compressor C and the gas defrost header coupling to transport heated, compressed gaseous refrigerant to the gas defrost header 66. In the illustrated schematic, the refrigeration line R2 taps into or fluidly connects with refrigeration line R4 to communication with the outlet of the compressor C. Alternatively, the compressor C may incorporate a second discharge outlet (not shown) to directly connect to the refrigeration line R2.

From the outlet of the condenser CN, compressed liquid refrigerant is discharged for accumulation in a receiver RC. From the receiver RC, the compressed liquid refrigerant flows through a defrost differential valve DDV before being transported to the liquid header 62 via the refrigeration line R3. Alternatively, the defrost differential valve DDV may be positioned upstream of the condenser CN and downstream of where the refrigerant line R2 taps into or fluidly connects with the refrigerant line R4. The defrost differential valve DDV is operable to cause a relatively small pressure drop across the valve DDV and is discussed in more detail below.

The first refrigerated merchandiser M1 is shown operating in a normal refrigeration mode, whereby compressed liquid refrigerant is transported to the merchandiser M1, and low-pressure gaseous refrigerant is transported from the merchandiser M1. More particularly, in the first header module H1 (see FIG. 3), the liquid isolation valve 126 is opened and the liquid valve 118 is controlled to allow a metered amount of compressed liquid refrigerant to exit the first header module H1 via the liquid coupling 110.

From the liquid coupling 110, as shown in FIG. 4, the compressed liquid refrigerant is transported to the first refrigerated merchandiser M1 via a refrigeration line R5. The refrigeration line R5 may also be formed from copper tubing that is inserted into the liquid coupling 110 and brazed to the coupling 110. In the illustrated construction, an expansion valve 158 is shown positioned in the first refrigerated merchandiser M1 and in fluid communication with the refrigeration line R5 and a first evaporator EV1. Alternatively, more than one evaporator 14 may be utilized in a parallel or series arrangement in the first refrigerated merchandiser M1.

During normal refrigeration mode of the first refrigerated merchandiser M1, low-pressure gaseous refrigerant exits the first evaporator EV1 and is routed back to the first header module H1 via another refrigeration line R6. The refrigeration line R6 is fluidly connected to the suction coupling 86, such that the low-pressure gaseous refrigerant is transported to the suction header 58 through the open suction valve 94 and the open suction isolation valve 102. The refrigeration line R6 may also be formed from copper tubing that is inserted into the suction coupling 86 and brazed to the coupling 86. From the suction header 58, the low-pressure gaseous refrigerant may be drawn into the suction inlet of the compressor C to repeat the refrigeration cycle.

Alternatively, the low-pressure gaseous refrigerant may be drawn into the suction inlet of the compressor C, pressurized by the compressor C, and discharged from the compressor C for use in a defrost cycle. The second refrigerated merchandiser M2 is shown operating in a defrost mode, whereby heated, compressed gaseous refrigerant is transported to the merchandiser M2, and cooled, compressed substantially liquid refrigerant is transported back to the second header module H2 from the merchandiser M2. More particularly, in the second header module H2 (see FIG. 3), one or both of the suction isolation valve 102 and the suction valve 94 may close to prevent refrigerant flow into the common suction header 58. The gas defrost isolation valve 142 may then open, and the gas defrost valve 142 may control the amount of heated, compressed gaseous refrigerant that flows out of the gas defrost header 66 to exit the second header module H2 via the suction coupling 86.

From the suction coupling 86 of the second header module H2, as shown in FIG. 4, the heated, compressed gaseous refrigerant is transported from the suction coupling 86 to a second evaporator EV2 via another refrigeration line R7. The heated, compressed gaseous refrigerant may be at least partially condensed while flowing through the second evaporator EV2, as a result of the heat transfer from the refrigerant to the second evaporator EV2 to melt accumulated frost on the evaporator EV2. Subsequently, the cooled, compressed liquid refrigerant exiting the second evaporator EV2 is transported back to the second header module H2 via another refrigeration line R8, which is fluidly connected to the liquid coupling 110 of the second header module H2.

With reference to FIG. 3, upon re-entering the second header module H2, the cooled, compressed liquid refrigerant may flow past the open liquid valve 118, past the open liquid isolation valve 126, and into the liquid header 62 to mix with compressed liquid refrigerant discharged from the receiver RC. Thus, the cooled, compressed liquid refrigerant that was used in a defrost cycle in the second refrigerated merchandiser M2 may, for example, flow through the liquid header 62 and be used in a normal refrigeration cycle in the first refrigerated merchandiser M1.

As such, one or more header modules 10 in a plurality of interconnected header modules 10 may be configured, at any given time, in a defrost mode while other header modules 10 are configured in a normal refrigeration mode. The previously-mentioned defrost differential valve DDV permits this to occur. With reference to FIG. 4, when at least one header module 10 in a plurality of interconnected header modules 10 switches from a normal refrigeration mode to a defrost mode, the defrost differential valve DDV is actuated to cause a relatively small drop in pressure of the compressed liquid refrigerant across the valve DDV. This, in effect, creates a relatively small difference in pressure between the gas defrost header 66 and the liquid header 62. Such a difference in pressure is sufficient to cause the heated, compressed gaseous refrigerant in the gas defrost header 66 to flow through a particular refrigerated merchandiser 18 in a defrost mode (e.g., the second refrigerated merchandiser M2) and return to the liquid header 62 as a cooled, compressed substantially liquid refrigerant. The defrost differential valve DDV may, for example, be configured to drop the pressure of the compressed liquid refrigerant flowing through the valve DDV approximately 15-30 psi.

The header modules 10 may be prefabricated, such that they may be interconnected or assembled to form a complete header system in a relatively small amount of time. In addition, the method of assembling or interconnecting the header modules 10 (e.g., by using the dovetail-shaped keys 74 and keyways 78) decreases the labor associated with assembling the complete header system since the skilled labor typically required to braze together complicated sections of copper tubing is substantially decreased. 

1. A header module adapted for use with a retail store refrigeration system including a plurality of refrigerated merchandisers, the header module comprising: a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant received from the plurality of refrigerated merchandisers; and a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant for discharge to the plurality of refrigerated merchandisers, wherein the first and second conduits are integrally formed.
 2. The header module of claim 1, further comprising: a first end plate coupling the first conduit and second conduit; and a second end plate coupling the first conduit and second conduit, the second end plate positioned on the header module opposite the first end plate.
 3. The header module of claim 2, wherein the first and second end plates are configured with grooves, and wherein the header module includes a key configured to be selectively received within at least one of the grooves of the first and second end plates.
 4. The header module of claim 3, wherein the key is configured with a dovetail shape.
 5. The header module of claim 1, further comprising a suction inlet passageway through the header module and in communication with the first conduit.
 6. The header module of claim 5, further comprising a suction coupling positioned in the suction inlet passageway, wherein the suction coupling is configured to receive a refrigeration line carrying low-pressure gaseous refrigerant from at least one of the plurality of refrigerated merchandisers.
 7. The header module of claim 5, further comprising: a suction valve positioned in the suction inlet passageway, the suction valve being controllable to regulate flow of low-pressure gaseous refrigerant through the suction inlet passageway; and a suction isolation valve positioned in the suction inlet passageway to selectively block flow of low-pressure gaseous refrigerant through the suction inlet passageway.
 8. The header module of claim 1, further comprising a liquid outlet passageway through the header module and in communication with the second conduit.
 9. The header module of claim 8, further comprising a liquid coupling positioned in the liquid outlet passageway, wherein the liquid coupling is configured to receive a refrigeration line for carrying compressed liquid refrigerant to at least one of the plurality of refrigerated merchandisers.
 10. The header module of claim 8, further comprising: a liquid valve positioned in the liquid outlet passageway, the liquid valve being controllable to regulate flow of compressed liquid refrigerant through the liquid outlet passageway; and a liquid isolation valve positioned in the liquid outlet passageway to selectively block flow of compressed liquid refrigerant through the liquid outlet passageway.
 11. The header module of claim 1, further comprising: a third conduit defining at least a portion of a common gas defrost header adapted to carry superheated, compressed gaseous refrigerant for selective discharge to the plurality of refrigerated merchandisers, wherein the first, second, and third conduits are integrally formed.
 12. The header module of claim 11, further comprising a gas defrost passageway through the header module and in communication with the third conduit.
 13. The header module of claim 12, further comprising: a gas defrost valve positioned in the gas defrost passageway, the gas defrost valve being controllable to regulate flow of superheated, compressed gaseous refrigerant through the gas defrost passageway; and a gas defrost isolation valve positioned in the gas defrost passageway to selectively block flow of superheated, compressed gaseous refrigerant through the gas defrost passageway.
 14. The header module of claim 12, further comprising a suction inlet passageway through the header module and in communication with an evaporator in one of the plurality of refrigerated merchandisers, wherein the gas defrost passageway is selectively fluidly connected with the suction inlet passageway to deliver superheated, compressed gaseous refrigerant to the evaporator.
 15. A modular header system adapted for use with a retail store refrigeration system, the modular header system comprising: a first header module including a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant; and a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant; wherein the first conduit and second conduit of the first header module are integrally formed; and a second header module including a first conduit defining at least a portion of the common suction header; a second conduit defining at least a portion of the common liquid header; wherein the first conduit and second conduit of the second header module are integrally formed, and wherein the second header module is coupled to the first header module to fluidly couple the first conduits of the common suction header and the second conduits of the common liquid header.
 16. The modular header system of claim 15, wherein the first header module includes a plate positioned toward respective ends of the first conduit and second conduit of the first header module, and wherein the second header module includes a plate positioned toward respective ends of the first conduit and second conduit of the second header module.
 17. The modular header system of claim 16, wherein the first and second plates are configured with grooves, wherein the modular header system further comprises a key, and wherein the grooves are configured to receive the key.
 18. The modular header system of claim 17, wherein the key is configured with a dovetail shape.
 19. The modular header system of claim 15, further comprising a suction inlet passageway through each of the first and second header modules, the suction inlet passageways communicating with the respective first conduits of the common suction header.
 20. The modular header system of claim 19, further comprising a suction coupling positioned in each suction inlet passageway, wherein the suction couplings are each configured to receive a refrigeration line carrying low-pressure gaseous refrigerant from a respective refrigerated merchandiser.
 21. The modular header system of claim 19, further comprising: a suction valve positioned in each of the suction inlet passageways of the first and second header modules, the suction valves being controllable to regulate flow of low-pressure gaseous refrigerant through the respective suction inlet passageways; and a suction isolation valve positioned in each of the suction inlet passageways to selectively block flow of low-pressure gaseous refrigerant through the respective suction inlet passageways.
 22. The modular header system of claim 15, further comprising a liquid outlet passageway through each of the first and second header modules, the liquid outlet passageways communicating with the respective second conduits of the common liquid header.
 23. The modular header system of claim 22, further comprising a liquid coupling positioned in each liquid outlet passageway, wherein the liquid couplings are each configured to receive a refrigeration line carrying compressed liquid refrigerant to a respective refrigerated merchandiser.
 24. The modular header system of claim 22, further comprising: a liquid valve positioned in each of the liquid outlet passageways of the first and second header modules, the liquid valves being controllable to regulate flow of compressed liquid refrigerant through the respective liquid outlet passageways; and a liquid isolation valve positioned in each of the liquid outlet passageways to selectively block flow of compressed liquid refrigerant through the respective liquid outlet passageways.
 25. The modular header system of claim 15, wherein the first header module includes a third conduit defining at least a portion of a common gas defrost header adapted to carry superheated, compressed gaseous refrigerant, wherein the first, second, and third conduits of the first header module are integrally formed, wherein the second header module includes a third conduit defining at least a portion of the common gas defrost header, wherein the first conduit, second conduit, and the third conduit of the second header module are integrally formed, and wherein the second header module is coupled to the first header module to fluidly couple the third conduits of the common gas defrost header.
 26. The modular header system of claim 25, further comprising a gas defrost passageway through each of the first and second header modules, the gas defrost passageways communicating with the respective third conduits of the common gas defrost header.
 27. The modular header system of claim 26, further comprising: a gas defrost valve positioned in each of the gas defrost passageways of the first and second header modules, the gas defrost valves being controllable to regulate flow of superheated, compressed gaseous refrigerant through the respective gas defrost passageways; and a gas defrost isolation valve positioned in each of the gas defrost passageways to selectively block flow of superheated, compressed gaseous refrigerant through the respective gas defrost passageways.
 28. The modular header system of claim 26, further comprising a suction inlet passageway through each of the first and second header modules, the respective suction inlet passageways communicating with an evaporator in a refrigerated merchandiser, wherein the gas defrost passageways are selectively fluidly connected with the respective suction inlet passageways of the first and second header modules to deliver superheated, compressed gaseous refrigerant to the respective evaporators.
 29. The modular header system of claim 25, wherein one of the first and second header modules is coupled to a suction inlet of a compressor via a first refrigeration line, wherein the one of the first and second header modules is coupled to an outlet of a liquid receiver via a second refrigeration line, and wherein the one of the first and second header modules is coupled to a discharge outlet of the compressor via a third refrigeration line.
 30. The modular header system of claim 25, further comprising a valve positioned downstream of a discharge outlet of a compressor and upstream of the common liquid header defined by the first and second header modules, wherein the valve selectively causes a pressure differential between the common liquid header and the common gas defrost header defined by the first and second header modules.
 31. A method of assembling a retail store refrigeration system including a plurality of refrigerated merchandisers, the method comprising: providing a first header module including a first conduit defining at least a portion of a common suction header adapted to carry low-pressure gaseous refrigerant received from the plurality of refrigerated merchandisers; a second conduit defining at least a portion of a common liquid header adapted to carry compressed liquid refrigerant for discharge to the plurality of refrigerated merchandisers, the first conduit and second conduit of the first header module being integrally formed; providing a second header module including a first conduit defining at least a portion of the common suction header; a second conduit defining at least a portion of the common liquid header; the first conduit and the second conduit of the second header module being integrally formed; interconnecting the second header module with the first header module; and fluidly coupling the first conduits of the common suction header and the second conduits of the common liquid header.
 32. The method of claim 31, wherein providing a first header module includes providing a first header module having a third conduit defining at least a portion of a common gas defrost header adapted to carry superheated, compressed gaseous refrigerant for selective discharge to the plurality of refrigerated merchandisers, the first conduit, second conduit, and the third conduit of the first header module being integrally formed, wherein providing a second header module includes providing a second header module having a third conduit defining at least a portion of the common gas defrost header, the first conduit, second conduit, and the third conduit of the second header module being integrally formed, wherein fluidly coupling includes fluidly coupling the third conduits of the common gas defrost header.
 33. The method of claim 32, wherein interconnecting the second header module with the first header module includes engaging a key with grooves located on the first and second header modules.
 34. The method of claim 32, further comprising controlling a suction valve positioned in a suction inlet passageway in at least one of the first and second header modules to regulate flow of low-pressure gaseous refrigerant through the suction inlet passageway of the at least one of the first and second header modules.
 35. The method of claim 34, further comprising: controlling the suction valve to block flow of low-pressure gaseous refrigerant through the suction inlet passageway of at least one of the first and second header modules; and controlling a gas defrost valve positioned in a gas defrost passageway in the at least one of the first and second header modules to regulate flow of superheated, compressed gaseous refrigerant through the gas defrost passageway and through the suction inlet passageway of the at least one of the first and second header modules.
 36. The method of claim 32, further comprising controlling a liquid valve positioned in a liquid outlet passageway in at least one of the first and second header modules to regulate flow of compressed liquid refrigerant through the liquid outlet passageway of the at least one of the first and second header modules.
 37. The method of claim 32, further comprising: coupling one of the first and second header modules to a suction inlet of a compressor via a first refrigeration line; coupling the one of the first and second header modules to an outlet of a liquid receiver via a second refrigeration line; and coupling the one of the first and second header modules to a discharge outlet of the compressor via a third refrigeration line.
 38. The method of claim 32, further comprising: mounting a suction coupling in a suction inlet passageway in at least one of the first and second header modules; securing a refrigeration line to the suction coupling; and fluidly connecting the refrigeration line to an outlet of an evaporator in one of the plurality of refrigerated merchandisers.
 39. The method of claim 38, wherein securing the refrigeration line to the suction coupling includes brazing the refrigeration line to the suction coupling.
 40. The method of claim 32, further comprising: mounting a liquid coupling in a liquid outlet passageway in at least one of the first and second header modules; securing a refrigeration line to the liquid coupling; and fluidly connecting the refrigeration line to an inlet of an evaporator in one of the plurality of refrigerated merchandisers.
 41. The method of claim 40, wherein securing the refrigeration line to the liquid coupling includes brazing the refrigeration line to the liquid coupling. 